Did you notice that most of the answers you get are not so much about a particular race order but rather about the best way to start?
I'm just starting my 7th time (don't ask) through the game at this point and have discovered the old addage about "lot's of ways to skin a cat" is particularly true with GT3. The race order will define itself for you depending on how you choose to start and how you decide to modify it as you progress.
Be sure to see the most helpful prize car pages on this site
here to help you decide what race you can go to and win a particular car for a specific venue.
Also, you will want to look over one of the single most helpful tools one of the moderators (Der Alta) took the time to put together
here. It is basically an exhaustive detail on how he ran his game from start to finish and is well worth the look see.
As for the start of the game... I have my opinions too. To that end, I think
neon_duke is right about if you know how to drive and are willing to take the time to gold the B license for the Miata LS... then go right to the Roadster Enduro. Makes for a sweet start that puts you well ahead of the game early.
If you don't want to take the time and have decided to purchase a car for your game start, there are several schools of thought here with about four of them standing out. First car purchases that seem to be most popular are the Miata (J), the Vitz, the Trueno, and the PT Cruiser.
Of the four, I personally think the the best car is the Miata (J). However, having started and finished the game each way, it is my opinion the best first purchase is actually the Vitz since it can be used for the Front Wheel Drive races in addition to many other more standard races including both the Turbo and the NA races. You will win a Miata (J) and a Trueno from the Sunday and Clubman races right out of the pipe so why waste the money to buy them? In favor of the Vitz also is that you will eventually need a front wheel drive vehicle for the FF races as well as specifically a Vitz for the Vitz series races in both Beginner and Pro leagues. Yes everyone... I know it will be won in the first FF race but you need a FF car to race that anyway and you can sell the Vitz you win for parts (unless pink is your color).
The one thing I will add is the nod to the above being an argument for the PT Cruiser since it is FF too as I recall. It might even be the smarter buy but, I never liked it much so I dropped it off as soon as I won my first Trueno/Miata/Vitz combo for the first three series. Bit of a novelty barge if you ask me but can certainly win the key first three.
Another option that is a little more time consuming but gives the advantage of developing your skills to a very high level is to take the time to beat all the time trials and win the Panoz which gives you the option of selling it for about $500,000 game cash for a killer start on cash.
The absolute best start for the game is to gold every license and beat the Time Trials first because of the cars you win from that. Gives you choices and skills beyond anything the game will throw at you. Be advised, it is tough as nails to do. Ask anyone who isn't an ego... My opinion is to save that for later.
What order to actually start? Well, if you choose to buy your first car, go with the Sunday Cup and Clubman Cup to pick up your Miata and Trueno to go with your Vitz and follow your nose from there.
Here is my two cents to power upgrades etc... I have won the entire beginner series and the first couple three amateur races on "normal" tires several times easily. In fact, driving on "normal" tires for awhile I think makes you a better driver who is better prepped for the later races where pit strategy comes into play. Second penny goes to Turbo Stage 1 as my thoughts for best buy for the money in beginner.
phattboy